The present invention relates to a process for fabricating metallic structures utilizing flow forming and bonding. Flow forming is a process where a part is formed by the use of heat and compressive pressure. It is to be distinguished from superplastic forming where parts are drawn under tensile stress. The part to be formed is placed within tooling and heated to the temperature at which the part material becomes plastic. Pressure is then applied to the tooling to flow the part material into the shape dictated by the tooling. The major object of the flow forming process is to form a structure to substantially net shape to thereby reduce conventional machining and obviate the need where possible for a plurality of parts which must be joined to form the final structure.
A method of flow forming is described in U.S. Pat. No. 3,519,503 to Moore, et al. In this method, high strength alloys are heated to a temperature placing them in a condition of low strength and high ductility and forged in hot dies to a desired shape. However, with such state of the art flow forming methods, limited hardware configurations are available. It is normally quite difficult, if not impossible, to fabricate some hardware designs such as thin webs and stiffeners using state of the art flow forming (also known as hot die forging) processes because of the difficulty in causing the material to flow into narrow cavities or thin sections or other desirable design configurations. For some parts, it is necessary with state of the art methods to produce special preform configurations to assure that the finished part can be readily produced in the final operation. Such preforms require either machining or preform dies and add cost to the finished part.